The present invention relates to a mechanical transmission for agricultural vehicles of adjustable track width.
More particularly it relates to a mechanical transmission of this type which is to be adapted to agricultural machines designed for agrochemical spraying, liquid fertilizer application, etc., that require the machine to move over the culture with its tires passing between the plant rows.
It is known for agricultural machine to be elevated to pass over the plants of a certain culture. The rear axles of these machines are mounted to lower bearings of a gear case, which extend upwards where they encounter the input shaft of the machine transmission. In these conventional machines the differential is fixed to the chassis structure, and from it the axle shafts extend with universal joint shafts and retractable axles, which engage to the upper gears of the cases that transmit motion to the wheels. The universal joint shafts are essential to compensate the vertical motions of the rear suspension in relation to the chassis of the vehicle. However, the presence of the universal joint shafts delimits the transverse space available between the rear wheels and therefore delimits the track width alteration from a maximum value to a minimum value. Thus, a track width change of a machine can not be carried out by only one pair of retractable axles but requires other pairs of retractable axles with other length, which in turn requires disassembling and reassembling of the machine for such replacement.
When the agricultural vehicle of adjustable track width has a mechanical transmission, the track width change requires more than a single alteration of the distance between the wheels, even if it is carried out with assistance of hydraulic cylinders. The intervention must be made in a workshop and even occasionally in the field, however with the machine stopped because some components must be replaced.
Accordingly, it is an object of the present invention to provide a mechanical transmission for agricultural vehicles of adjustable track width, which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a mechanical transmission for agricultural vehicles of adjustable track width, which does not require a replacement of the components, allowing the track width adjustment of the machine to be carried out without stopping the machine at a workshop.
It is another object of the present invention to provide a mechanical transmission for agricultural vehicles of adjustable track width, which maintains the needed axles alignment, dispensing with the use of universal joint shafts, thus allowing the track width change with the machine in motion.
Finally, it is still another object of the present invention to provide a mechanical transmission for agricultural vehicles of adjustable track width, which configures a track width adjusting system to adapt the machine to any row spacing or plant row, for various types of cultures.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a mechanical transmission for agricultural vehicles of adjustable track width, which has gear cases disposed vertically to elevate a chassis height of the machine above a plantation; rear axles provided for wheels of the machine and mounted to said gear cases; first gears and second gears located in said gear cases and coupling said axles and also being interconnected with one another; a differential to which torque is transmitted from said axles through said second gears; a cross tube, said gear cases having substantially first extensions which are fitted on said cross tube so as to allow sliding outwards or inwards of said extensions in order to modify a machine track width, said differential having two further extensions; grooved shafts which are fixedly connected to said second gears; first tube bushings which are connected with said gear cases and in which said grooved shafts are fitted; second bushings having internal grooves and surrounding said grooved shafts; tubes which are fixed to said gear cases concentrically to said gears, said second extensions of said differential being fitted in a sliding and tight way within said tubes concentrically to said second gears, acting as a support to a differential assembly which is suspended by said gear cases.
When the mechanical transmission for agricultural vehicles of adjustable track width is designed in accordance with the present invention, it eliminates the disadvantages of the prior art and provides for the above mentioned highly advantageous results.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
FIG. 1 is a plan view of a chassis and a transmission assembly of an agricultural vehicle with an installed mechanical transmission for adjustable track width in accordance with the present invention;
FIG. 2 is a side elevational view of the assembly shown in FIG. 1 with the mechanical transmission for adjustable track width;
FIG. 3 is a view showing the longitudinal section of a traction rear axle with corresponding parts of the transmission;
FIG. 4 is a partial plan view of a detail of the mechanical transmission for adjustable track width with the rear axle showing a totally reduced track width; and
FIG. 5 is an enlarged side view of a device that prevents a differential housing from rotating, allowing a radial displacement of the same.